1. Field of the Invention
The present invention generally relates to a moving mechanism using a piezoelectric actuator and, more particularly, to a magnetic disk apparatus having a micro moving mechanism for moving a magnetic head by an extremely small distance by using an actuator for moving the magnetic head using a piezoelectric element
2. Description of the Related Art
In recent years, miniaturization and precision of information equipments have progressed, and a demand for an actuator that can realize a minute movement with high accuracy is increasing. For example, a micro-actuator that can control a minute movement is required for a focus correction or an inclination angle control of an optical control or a head actuator of an ink-jet printer and a magnetic disk apparatus.
In such a situation, with an expansion in a market and a change to high-performance apparatus, an increase in a recording capacity is increasingly apt to be important. Generally, an increase in a storage capacity of a magnetic disk apparatus can be achieved by increasing a storage capacity per a single disk. In order to attain high recording density without changing a size of a disk, i.e., a diameter of a disk, it is indispensable to increase a number (TPI) of tracks per unit length, i.e., to reduce a width of each track. For this reason, it is required to achieve higher position accuracy of a head in a direction of width of a track, and development of a micro-actuator for a head that can achieve high positioning accuracy.
In conventional head positioning, a core-earth actuator provided in a fixing part of a suspension supporting a head (slider) has been used. Conventionally, this method was able to sufficiently cover a recording density of a medium. However, due to high-densification of recording density with recent increase in storage capacity of recording apparatuses, the positioning accuracy according to the conventional method becomes insufficient, which may cause occurrence of defects in reading and writing by a head.
Thus, as a method for improving positioning accuracy of a head, a method of providing a micro-actuator, which directly moves a slider, between the slider and a suspension is suggested (for example, refer to patent document 1 listed below). The micro-actuator is capable of minutely moving the head mounted on an end of an arm independently of an operation of a core-earth actuator. The following patent documents disclose conventional technique relevant to the present invention.    Patent Document 1: Japanese Laid-Open Patent Application No. 2002-74870    Patent Document 2: Japanese Laid-Open Patent Application No. 2001-167545    Patent Document 3: Japanese Laid-Open Patent Application No. 2001-84723
In the structure having a micro-actuator disclosed in the above patent document 1, there is a problem in that a variation may occur in the minute movement of a slider.